<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="./lib/vue.js"></script>
</head>
<body>
<div id="root">
  <child></child>
  <child></child>
</div>
</body>
<script>
    const state={
      num:100
    }
    new Vue({
        el: '#root',
        data: {
          num:200
      },
      components: {
          Child: {
            data(){
              return {
                num:100
              }
              // return state
            },
            template:` <button @click="num++">{{num}}</button>`
          }
      }

    })
</script>
</html>